Little is known of the local or systemic immune responses to the microorganisms associated with root caries. This proposal will approach this problem by measuring levels of systemic and parotid salivary antibody to supragingival antibody to potential root caries pathogens in crevicular fluids and minor salivary gland fluids in these subjects. If the bacteria in the advancing front of the root caries lesion are representative of the organisms responsible for root caries, then pulp exposure may act as a systemic injection. This may result in a seriological identification of these organisms. Therefore, we will measure levels of systemic antibody (in serum) to potential root caries pathogens in individuals who have recently undergone pulp exposure as a result of root caries. Finally, we will attempt to uncover the dynamic aspects of the local and systemic immune responses to changing disease relationships by measuring, in a longitudinal fasion, changes in local and systemic antibody to a battery of homologous microorganisms suspected as root caries pathogens in subjects with active root caries. These studies, in coordination with independent studies of the microbiological characteristics of these sites, should help us to identification of the etiology of the root caries disease process.